Stabilizing cellulose yarns



Patented Dec. 4, 1951 2,571,593 STABILIZING CELLULOSE YARNS Jeilerson A. Stokes, Richmond, Va., assignor to E. I. du Pont de Nemours & Company, Wilmington, DeL, a corporation of Delaware No Drawing. Application December 21, 1946, Serial No. 717,813

6 Claims.

This invention relates to cellulosic yarns. threads, cords and the like, and more particularly, it relates to the treatment of cellulosic yarns, threads, cords and the like with a material for. increasing the rcsistance of such structures to deterioration by heat.

Certain cellulosic yarns, for example, regenerated cellulose yarns, have the disadvantages characteristic of deteriorating to a considerable extent when subjected to elevated temperatures- While certain materials, such as urea, have been used successfully as heat aging inhibitors, more effective agents have been desired to reduce even further the extent of deterioration in the yarns.

It isan object of the present invention to treat cellulosic yarns in such a manner as to increase their resistance to deterioration by heat.

It is another object of this invention to treat certain cellulosic yarns, for example, regenerated cellulose yarns having a high dry tenacity, in such a manner that the resultant yarns will have an increased resistance to deterioration by heat.

It is a further object of this invention to prepare articles containing cellulosic yarns, particularly regenerated cellulose yarns, which articles are suitable for use at elevated temperatures.

"A still more specific object of the present invention is the production of rubber goods reinforced with cellulosic yarns, for example, regenerated cellulose yarns which have been treated in such a manner as to increase their resistance to deterioration by heat.

Other objects of the invention will appear hereinafter.

,The objects of the invention may be accomplished, in general, by intimately associating cellulosic yarns, for example, regenerated cellulose yarns, with l-phenylbiguanide, and drying the same. Other factors being equal, the degree of increased resistance to deterioration by heat of the cellulosic yarns thus treated will be proportional to the amount of l-phenylbiguanide with which they are impregnated, up to a certain limit.

' In accordance with the present invention, it has been-discovered that cellulosic threads, for example, regenerated cellulose threadsuch as viscose rayon threads, or cuprammonium rayon thread, may be stabilized against the deteriorative action of heat by impregnation of the thread with l-phenylbiguanide. Whereas van untreated regenerated cellulose thread, subjected to heating for a period of 32 hours at a temperature of 150 C., shows a loss of strength of about 100%, the same yarn, when impregnated with 0.22% 1- phenylbiguanide shows on heating for 32 hours at 150 C. a loss of strength of only 32%.

The examples given below are typical ofthe methods used toprepare cellulosic threads stabili2ed with l-phenylbiguanide against the deterior'ative action of heat. These examples are illustrative only and are not to be construed as limitative.

EXAMPLE I A given length of high tenacity regenerated cellulose yarn made by the viscose process and consisting of 1100 denier, 480 filaments and no twist (1100-480-0) was immersed in a bath consisting of one part of l-phenylbiguanide and 99 parts of water maintained at a temperature of C. A continuous strand of the yarn is passed through the bath. This is accomplished by running the yarn over a simple system of freely rotating pulleys so as to give a length of yarn of about 100 cm. immersed a any instant and being wound up on a mechanic lly driven reel. The reel is rotated at such a speed that the rate of traverse of the yarn through the bath is about 230. cm. per second and the period of immersion is, therefore, about 0.5 second. After passing through the bath, the yarn is allowed to remain on the reel until dry.

The yarn treated in this fashion will have increased in weight by the impregnation with l-phenylbiguanide so that after drying it will contain about 0.22% of the modifier. Whereas the yarn initially possessed a strength of about 4.0 grams per denier, after the above treatment its strength is 4.0 grams per denier. After exposure in a sealed tube to a temperature of C. for 4 hours, the strength is decreased to 3.42 grams per denier, a loss of about 15 per cent of its original strength. An untreated yam e posed to the same heat treatment has a loss of about 49%.

A EXAMPLE 11 Given lengths of the same viscose rayon yarn as in Example I above are treated in precisely the same manner except that the heat aging is increased successively up to 40 hours. A comparison of the loss in strength of the various treated yarns as compared to the controls is given in Table I.

.l-phenylbiguanide in small amounts is an effective inhibitor of heat aging. Without the inhibitor the yarn deteriorates rapidly and extensively, for example, 80% of its strength being lost after 24 hours. In contrast yarn containing only 0.22% l-phenylbiguanide deteriorated to a considerably lesser extent (54%) after a longer time (40 hours) Y Since urea has been disclosed in U. S. 2,278,285 as an effective heat-aging inhibitor for cellulosic materials, the effectiveness of l-phenylbiguanide was compared to that of urea. Accordingly, the same yarn was impregnated by the above described methods so that it contained 0.99% urea. Comparable aging treatments were given to the urea modified yarns. Table I above. These figures show that, in general, l-phenylbiguanide is a very eflicient inhibitor and is more eflicient than urea, since losses in strength are lower even though the concentrations of l-phenylbiguanide used were only about one-fifth of the concentrations of urea that were used.

EXAMPLE 111 To compare the effectiveness of l-phenylbiguanide and urea at similar concentration levels, yarn identical to that used in Example I was impregnated with urea so that the final yarn contained 0.25% urea. Samples of this were then aged at 4, 8, 16 and 24 hours in a sealed tube at 150 C. Strength losses were measured and compared to yarn similarly treated but con- A comparison shows the unusually good efiec-, tiveness of the I-phenylbiguanide. The outstandin efliciency of this agent as a heat-aging inhibitor at low concentrations is important in that smaller amounts of agent are required. It is well known that the fatigue life of rayon cords is adversely affected by an excess of salts on the yarn. For this reason it is preferred to use l-phenylbiguanide which may be employed in small amounts and yet at greater effectiveness.

The method of impregnation consists simply in the immersion of the yarn in an aqueous solution of 1-phenylbiguanide of the desired concentration at whatever temperature is required to maintain the l-phenylbiguanide in solution for a suitable period of time. is accomplished either by passing a single thread of the yarn continuously through a bath of the solution with a suitable length of yarn immersed at any instant and at .a suitable rate of travel. Or, the immersion may be accomplished by simply dipping an entire skein in the solution and allowing it to remain there for a suitable length of time. If the impregnation is by passage of the single strand of yarn through a bath, it is important that this be done without the application of undue tension to the yarn or with as little tension as is practicable in order to. at-

tain the greatest stabilizing activity from a given amount of l-phenylbiguanide.

The results are given in The immersion If, on the other hand, the impregnation is by dipping a skein of the yarn in the bath al at once, the skein is freed of excessive liquor by wringing out in a centrifuge or by/other suitable means. In both methods, the concentration of the l-phenylbiguanide solution is determined by extent to which it is desired to impregnate the yarn. It is apparent that one may stabilize the yarn to the desired degree by varying the amount of l-phenylbiguanide applied to the yarn, or the extent of the impregnation. Effective results are obtained using concentrations of l-phenylbiguanide from about 0.1% to about 1.5% by weight of the yarns. Generally, it is preferred to use the agent in amounts from about 0.2% to about 0.5% by weight of the yarns.

Although it will generally be desired to treat .cellulosic threads according to the methods above described, solvents other than water may also be used. Instead of water, organic liquids or mixtures of these with or without water may be employed. For example, cyclohexane, benzene, chloroform, diethylether, carbon disulflde, ethyl acetate ethanol, acetone or methyl Cellosolve may be employed in the immersion baths as solvents for the l-bhenylbiguanide. Furthermore, it is possible to impregnate a thread such as viscose rayon yarn while still in the gel state. Also, any type of wetting agent which readily allows the yarn to be wetted by the solution may be used.

The treatment of cellulosic threads with 1- phenylbiguanide according to the methods described above may precede their treatment with a resin-latex adhesive preparation of the type described by Charch and Maney in their patent application, Serial No. 12,739, filed March 23. 1935, Patent No. 2,128,635, or any other adhesive treatment.

The methods 'of treatment of cellulosic threads described above whereby, through the intimate association of 'l-phenylbiguanide with cellulose. the resistance of the yarn to deterioration by heat is increased may be varied over a wide range. The yarn may be impregnated with 1- phenylbiguanide from any solvent for l-phenylbiguanide which is itself not deleterious to the particular yarn in question, and at whatever temperature is required to maintain the solution.

The tenacity values of the yarn as above expressed in grams per denier refer to the breaking strength of the yarn as determined by a Scott testing machine regulated under identical conditions with the same rate of loading.

The increased resistance to deterioration by heat imparted to the cellulosic yarn by the treatment makes the yarn particularly useful where it is to be subjected to elevated temperatures. Viscose rayon yarn or similar cellulosic yarns so treated to associate l-phenylbiguanide intimately with the yarn may be used for all purposes to which such a yarn might otherwise be put and which subject it eventually to elevated temperatures such as would more rapidly destroy the usefulness of the untreated than the treated yarn. The yarn treated according to this invention may be twisted into cords or other materials for use as reenforcement for rubber articles, including motor vehicle tires and steam hose. Such treated yarn will withstand, far better than the untreated yarn, deterioration during the manufacture of the rubber products involving such operations as vulcanization at elevated temperatures or in use where the products are subjected to elevated temperatures. Also, yarn so treated may, in one or another form, be woven into fabrics for uses at elevated temperatures such as the covering of laundry mangles, or as zinc oxide fume bags.

Among other uses for this treated yarn are covers and protectors for sun exposed objects such as awnings and beach umbrellas; automobile top materials; masks and protectors around steel furnaces and the like; fabric tubes for discharge ends of chutes for hot materials as in cement mills; bags for heating pads and electrically heated clothing; strainers for hot oil and other non-aqueous materials; belt driers such as on blueprint machines; and conveyor belts for hot materials.

Whereas present cellulosic yarn. such as viscose rayon yarn, is ordinarily deteriorated on exposure to heat, the present invention makes possible the treatment of this yarn so that it possesses a marked stability under the same conditions. The use of l-phenylbiguanide has the further advantage that impregnation of a cellulosic yarn will cause very little loss of the initial strength of the yarn. The use of 1- phenylbiguanide is furthermore advantageous in thgt it has a high decomposition point (150- 0.).

Since it is obvious that many changes and modifications can be made in the above described details without departing from the nature and spirit of the invention, it is understood that this invention is not to be limited except as set forth in the appended claims.

I claim:

1. The process of stabilizing regenerated cellulose yarns against deterioration by heat which comprises impregnating said yarns with 1- phenylbiguanide to the extent of at least 0.1% by weight of said yarns.

2. The process of stabilizing regenerated cellulose yarns against deterioration by heat which comprises treating said yarns with a solution of l-phenylbiguanide in such a manner as to impregnate said yams with l-phenylbiguanide to the extent of at least 0.1% by weight of said yarns, and drying the 1-phcnylbiguanide-lm-' pregnated yarns.

3. The process of stabilizing the regenerated cellulose yarns against deterioration by heat which comprises immersing said yarns in a solution of l-phenylbiguanide for a period of at least 0.5 second in such a manner as to impregnate said yarns with l-phenylbiguanide to the extent of at least 0.1% by weight of said yarns, and drying the i-phenylbiguanide-impregnated yarns.

4. The processs of stabilizing regenerated cellulose yarns against deterioration by heat which comprises passing said yarns through a solution of l-phenylbiguanide with a minimum amount of tension in such a manner as to impregnate said yarns with l-phenylbiguanide to the extent of at least 0.1% by weight of said yarns, and drying the l-phenylbiguanide-impregnated yarns.

5. The process of stabilizing regenerated cellulose yarns against deterioration by heat which comprises impregnating said yarns in the gel state of yarn formation with l-phenylbiguanide to the extent of at least 0.1% by weight of said yarns.

6. The process of stabilizing regenerated cellulose yarns against deterioration by heat which comprises immersing the said yarns in a bath containing 1 part of l-phenylbiguanide and 99 parts of water to impregnate thereby said yarns with said l-phenylbiguanide to the extent of at least 0.1% by weight of said yarns; and drying the resultant impregnated yarns.

JEFFERSON A. STOKES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,149,709 Rein Mar. 7, 1939 2,192,964 Dreyfus Mar. 12, 1940 2,221,333 Sibley Nov. 12, 1940 FOREIGN PATENTS Number Country Date 555, 761 Great Britain Sept. '7, 1943 

1. THE PROCESS OF STABILIZING REGENERATED CELLULOSE YARNS AGAINST DETERIORATION BY HEAT WHICH COMPRISES IMPREGNATING SAID YARNS WITH 1PHENYLBIGUANIDE TO THE EXTENT OF AT LEAST 0.1% BY WEIGHT OF SAID YARNS. 